<title>最短路径问题</title><link href="http://hzoi.com/tomorrow.css" rel="stylesheet"><div class="ui existing segment"><pre><code><span class="pl-cp">#include</span><span class="pl-cpf">&lt;iostream&gt;</span><span class="pl-cp"></span>
<span class="pl-cp">#include</span><span class="pl-cpf">&lt;cstdio&gt;</span><span class="pl-cp"></span>
<span class="pl-cp">#include</span><span class="pl-cpf">&lt;cmath&gt;</span><span class="pl-cp"></span>
<span class="pl-cp">#include</span><span class="pl-cpf">&lt;algorithm&gt;</span><span class="pl-cp"></span>
<span class="pl-cp">#define INF 0x3f3f3f3f</span>
<span class="pl-cp">#define N 1001</span>
<span class="pl-k">using</span> <span class="pl-k">namespace</span> <span class="pl-n">std</span><span class="pl-p">;</span>
<span class="pl-kt">int</span> <span class="pl-n">x</span><span class="pl-p">[</span><span class="pl-n">N</span><span class="pl-p">],</span><span class="pl-n">y</span><span class="pl-p">[</span><span class="pl-n">N</span><span class="pl-p">];</span>
<span class="pl-kt">double</span> <span class="pl-n">g</span><span class="pl-p">[</span><span class="pl-n">N</span><span class="pl-p">][</span><span class="pl-n">N</span><span class="pl-p">];</span>
<span class="pl-kt">double</span> <span class="pl-nf">calculate</span><span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">x1</span><span class="pl-p">,</span><span class="pl-kt">int</span> <span class="pl-n">y1</span><span class="pl-p">,</span><span class="pl-kt">int</span> <span class="pl-n">x2</span><span class="pl-p">,</span><span class="pl-kt">int</span> <span class="pl-n">y2</span><span class="pl-p">){</span>
    <span class="pl-k">return</span> <span class="pl-n">sqrt</span><span class="pl-p">((</span><span class="pl-kt">double</span><span class="pl-p">)(</span><span class="pl-n">x1</span><span class="pl-o">-</span><span class="pl-n">x2</span><span class="pl-p">)</span><span class="pl-o">*</span><span class="pl-p">(</span><span class="pl-n">x1</span><span class="pl-o">-</span><span class="pl-n">x2</span><span class="pl-p">)</span><span class="pl-o">+</span><span class="pl-p">(</span><span class="pl-kt">double</span><span class="pl-p">)(</span><span class="pl-n">y1</span><span class="pl-o">-</span><span class="pl-n">y2</span><span class="pl-p">)</span><span class="pl-o">*</span><span class="pl-p">(</span><span class="pl-n">y1</span><span class="pl-o">-</span><span class="pl-n">y2</span><span class="pl-p">));</span>
<span class="pl-p">}</span>
<span class="pl-kt">int</span> <span class="pl-nf">main</span><span class="pl-p">(){</span>
    <span class="pl-kt">int</span> <span class="pl-n">n</span><span class="pl-p">,</span><span class="pl-n">m</span><span class="pl-p">;</span>
    <span class="pl-n">cin</span><span class="pl-o">&gt;&gt;</span><span class="pl-n">n</span><span class="pl-p">;</span>
    <span class="pl-k">for</span><span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">i</span><span class="pl-o">=</span><span class="pl-mi">1</span><span class="pl-p">;</span><span class="pl-n">i</span><span class="pl-o">&lt;=</span><span class="pl-n">n</span><span class="pl-p">;</span><span class="pl-n">i</span><span class="pl-o">++</span><span class="pl-p">)</span>
        <span class="pl-n">cin</span><span class="pl-o">&gt;&gt;</span><span class="pl-n">x</span><span class="pl-p">[</span><span class="pl-n">i</span><span class="pl-p">]</span><span class="pl-o">&gt;&gt;</span><span class="pl-n">y</span><span class="pl-p">[</span><span class="pl-n">i</span><span class="pl-p">];</span>
    <span class="pl-n">cin</span><span class="pl-o">&gt;&gt;</span><span class="pl-n">m</span><span class="pl-p">;</span>
    <span class="pl-k">for</span><span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">i</span><span class="pl-o">=</span><span class="pl-mi">1</span><span class="pl-p">;</span><span class="pl-n">i</span><span class="pl-o">&lt;=</span><span class="pl-n">n</span><span class="pl-p">;</span><span class="pl-n">i</span><span class="pl-o">++</span><span class="pl-p">){</span>
        <span class="pl-k">for</span><span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">j</span><span class="pl-o">=</span><span class="pl-mi">1</span><span class="pl-p">;</span><span class="pl-n">j</span><span class="pl-o">&lt;=</span><span class="pl-n">n</span><span class="pl-p">;</span><span class="pl-n">j</span><span class="pl-o">++</span><span class="pl-p">){</span>
            <span class="pl-n">g</span><span class="pl-p">[</span><span class="pl-n">i</span><span class="pl-p">][</span><span class="pl-n">j</span><span class="pl-p">]</span><span class="pl-o">=</span><span class="pl-n">INF</span><span class="pl-p">;</span>
            <span class="pl-n">g</span><span class="pl-p">[</span><span class="pl-n">j</span><span class="pl-p">][</span><span class="pl-n">i</span><span class="pl-p">]</span><span class="pl-o">=</span><span class="pl-n">INF</span><span class="pl-p">;</span>
        <span class="pl-p">}</span>
        <span class="pl-n">g</span><span class="pl-p">[</span><span class="pl-n">i</span><span class="pl-p">][</span><span class="pl-n">i</span><span class="pl-p">]</span><span class="pl-o">=</span><span class="pl-mi">0</span><span class="pl-p">;</span>
    <span class="pl-p">}</span>
 
    <span class="pl-k">for</span><span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">i</span><span class="pl-o">=</span><span class="pl-mi">1</span><span class="pl-p">;</span><span class="pl-n">i</span><span class="pl-o">&lt;=</span><span class="pl-n">m</span><span class="pl-p">;</span><span class="pl-n">i</span><span class="pl-o">++</span><span class="pl-p">){</span>
        <span class="pl-kt">int</span> <span class="pl-n">u</span><span class="pl-p">,</span><span class="pl-n">v</span><span class="pl-p">;</span>
        <span class="pl-n">cin</span><span class="pl-o">&gt;&gt;</span><span class="pl-n">u</span><span class="pl-o">&gt;&gt;</span><span class="pl-n">v</span><span class="pl-p">;</span>
        <span class="pl-kt">double</span> <span class="pl-n">temp</span><span class="pl-o">=</span><span class="pl-n">calculate</span><span class="pl-p">(</span><span class="pl-n">x</span><span class="pl-p">[</span><span class="pl-n">u</span><span class="pl-p">],</span><span class="pl-n">y</span><span class="pl-p">[</span><span class="pl-n">u</span><span class="pl-p">],</span><span class="pl-n">x</span><span class="pl-p">[</span><span class="pl-n">v</span><span class="pl-p">],</span><span class="pl-n">y</span><span class="pl-p">[</span><span class="pl-n">v</span><span class="pl-p">]);</span>
        <span class="pl-n">g</span><span class="pl-p">[</span><span class="pl-n">u</span><span class="pl-p">][</span><span class="pl-n">v</span><span class="pl-p">]</span><span class="pl-o">=</span><span class="pl-n">temp</span><span class="pl-p">;</span>
        <span class="pl-n">g</span><span class="pl-p">[</span><span class="pl-n">v</span><span class="pl-p">][</span><span class="pl-n">u</span><span class="pl-p">]</span><span class="pl-o">=</span><span class="pl-n">temp</span><span class="pl-p">;</span>
    <span class="pl-p">}</span>
 
    <span class="pl-k">for</span><span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">k</span><span class="pl-o">=</span><span class="pl-mi">1</span><span class="pl-p">;</span><span class="pl-n">k</span><span class="pl-o">&lt;=</span><span class="pl-n">n</span><span class="pl-p">;</span><span class="pl-n">k</span><span class="pl-o">++</span><span class="pl-p">)</span>
        <span class="pl-k">for</span><span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">i</span><span class="pl-o">=</span><span class="pl-mi">1</span><span class="pl-p">;</span><span class="pl-n">i</span><span class="pl-o">&lt;=</span><span class="pl-n">n</span><span class="pl-p">;</span><span class="pl-n">i</span><span class="pl-o">++</span><span class="pl-p">)</span>
            <span class="pl-k">for</span><span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">j</span><span class="pl-o">=</span><span class="pl-mi">1</span><span class="pl-p">;</span><span class="pl-n">j</span><span class="pl-o">&lt;=</span><span class="pl-n">n</span><span class="pl-p">;</span><span class="pl-n">j</span><span class="pl-o">++</span><span class="pl-p">)</span>
                <span class="pl-k">if</span><span class="pl-p">(</span><span class="pl-n">g</span><span class="pl-p">[</span><span class="pl-n">i</span><span class="pl-p">][</span><span class="pl-n">j</span><span class="pl-p">]</span><span class="pl-o">&gt;</span><span class="pl-n">g</span><span class="pl-p">[</span><span class="pl-n">i</span><span class="pl-p">][</span><span class="pl-n">k</span><span class="pl-p">]</span><span class="pl-o">+</span><span class="pl-n">g</span><span class="pl-p">[</span><span class="pl-n">k</span><span class="pl-p">][</span><span class="pl-n">j</span><span class="pl-p">])</span>
                    <span class="pl-n">g</span><span class="pl-p">[</span><span class="pl-n">i</span><span class="pl-p">][</span><span class="pl-n">j</span><span class="pl-p">]</span><span class="pl-o">=</span><span class="pl-n">g</span><span class="pl-p">[</span><span class="pl-n">i</span><span class="pl-p">][</span><span class="pl-n">k</span><span class="pl-p">]</span><span class="pl-o">+</span><span class="pl-n">g</span><span class="pl-p">[</span><span class="pl-n">k</span><span class="pl-p">][</span><span class="pl-n">j</span><span class="pl-p">];</span>
    <span class="pl-kt">int</span> <span class="pl-n">u</span><span class="pl-p">,</span><span class="pl-n">v</span><span class="pl-p">;</span>
    <span class="pl-n">cin</span><span class="pl-o">&gt;&gt;</span><span class="pl-n">u</span><span class="pl-o">&gt;&gt;</span><span class="pl-n">v</span><span class="pl-p">;</span>
    <span class="pl-n">printf</span><span class="pl-p">(</span><span class="pl-s">&quot;%.2lf&quot;</span><span class="pl-p">,</span><span class="pl-n">g</span><span class="pl-p">[</span><span class="pl-n">u</span><span class="pl-p">][</span><span class="pl-n">v</span><span class="pl-p">]);</span>
    <span class="pl-k">return</span> <span class="pl-mi">0</span><span class="pl-p">;</span>
<span class="pl-p">}</span>
</cpde></pre></div>